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Request uncompressed format on Windows

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This commit is contained in:
Milan Nikolic
2026-06-30 12:14:42 +02:00
parent b92e633679
commit 9ce1726c4c
1 changed files with 40 additions and 11 deletions
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51
camera/camera_windows.go
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@@ -46,8 +46,7 @@ func New(opts Options) (camera *Camera, err error) {
return
}
// run sets up the capture window on a locked OS thread, reports the result over
// ready, then runs the win32 message loop.
// run sets up the capture window on a locked OS thread, reports the result over ready, then pumps messages.
func (c *Camera) run(ready chan<- error) {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
@@ -108,20 +107,45 @@ func (c *Camera) run(ready chan<- error) {
size := sendMessage(c.camera, wmCapGetVideoformat, 0, 0)
sendMessage(c.camera, wmCapGetVideoformat, size, uintptr(unsafe.Pointer(&bi)))
bi.BmiHeader.BiWidth = int32(c.opts.Width)
bi.BmiHeader.BiHeight = int32(c.opts.Height)
headerSize := uintptr(unsafe.Sizeof(bi.BmiHeader))
ret = sendMessage(c.camera, wmCapSetVideoformat, size, uintptr(unsafe.Pointer(&bi)))
if int(ret) == 0 {
ready <- fmt.Errorf("camera: can not set video format: %dx%d", int(c.opts.Width), int(c.opts.Height))
// Request an uncompressed format; the WDM mapper converts, and MJPG via grab is unreliable.
for _, f := range []struct {
compression uint32
bitCount uint16
}{
{biRGB, 24},
{biRGB, 32},
{yuy2FourCC, 16},
} {
stride := ((int(c.opts.Width)*int(f.bitCount) + 31) / 32) * 4
return
bi.BmiHeader.BiSize = uint32(headerSize)
bi.BmiHeader.BiPlanes = 1
bi.BmiHeader.BiWidth = int32(c.opts.Width)
bi.BmiHeader.BiHeight = int32(c.opts.Height)
bi.BmiHeader.BiCompression = f.compression
bi.BmiHeader.BiBitCount = f.bitCount
bi.BmiHeader.BiSizeImage = uint32(stride * int(c.opts.Height))
if int(sendMessage(c.camera, wmCapSetVideoformat, headerSize, uintptr(unsafe.Pointer(&bi)))) != 0 {
break
}
}
// Read back the format the driver actually accepted.
sendMessage(c.camera, wmCapGetVideoformat, headerSize, uintptr(unsafe.Pointer(&bi)))
c.format = bi.BmiHeader.BiCompression
sendMessage(c.camera, wmCapSetCallbackFrame, 0, syscall.NewCallback(c.callback))
rect := image.Rect(0, 0, int(c.opts.Width), int(c.opts.Height))
width := int(bi.BmiHeader.BiWidth)
height := int(bi.BmiHeader.BiHeight)
if height < 0 {
height = -height
}
rect := image.Rect(0, 0, width, height)
switch {
case c.format == 0:
@@ -222,10 +246,13 @@ func (c *Camera) Read() (img image.Image, err error) {
// Close closes camera.
func (c *Camera) Close() (err error) {
sendMessage(c.camera, wmCapSetCallbackFrame, 0, 0)
unregisterClass(c.className, c.instance)
sendMessage(c.camera, wmCapDriverDisconnect, 0, 0)
return destroyWindow(c.camera)
err = destroyWindow(c.camera)
unregisterClass(c.className, c.instance)
return err
}
// callback function.
@@ -278,6 +305,8 @@ const (
wsOverlappedWindow = 0x00CF0000
cwUseDefault = 0x7fffffff
biRGB = 0
)
// wndClassExW https://msdn.microsoft.com/en-us/library/windows/desktop/ms633577.aspx